Off-road utility vehicles often have dump boxes that may be loaded with cargo. These dump boxes are also commonly referred to as cargo boxes or cargo beds. The dump boxes may be used to hold most sorts of cargo and may be configured for hauling cargo and/or for dumping cargo.
The dump box may be used as a bed for holding large items. In the event that an item to be held cannot fit within the confines of the dump box, the dump box walls may be configured to collapse, fold, be removed, or otherwise be adjustable such that the dump box provides an at least partially unconfined bed. More specifically, it may be desirable to move the side walls of the dump box. Typically adjustment of the side walls has been accomplished either by pivoting the side walls along a horizontal axis such that they fold inwardly onto the dump box bed or outwardly to a generally vertical position beneath the plane of the dump box bed or by removing the side walls. Folding the side walls inwardly onto the dump box bed causes the resultant surface to be uneven, varying between the height of just the bed and the height of the bed with the side wall folded thereupon. Folding the side walls outwardly to a generally vertical position beneath the plane of the dump box bed may interfere with driving or free movement of the wheels of the utility vehicle. When removing the side walls entirely, it is necessary to find storage space for the side walls. Despite these concerns, collapsing or removing the side walls may still be desirable as objects that would not fit within the confines of the dump box bed can be loaded onto the dump box.
In some situations, the dump box may hold a volume of loose cargo, such as gravel, or material of which the component parts are large and have a tendency to cling together. When transporting, and particularly unloading, such cargo, it may be desirable for the dump box to have a mechanical or electromechanical lift mechanism to tip the box backwards and dump the cargo from the box.
Traditionally, tailgates are configured for opening in one of two ways: from the lower margin or from the upper margin. Opening from the lower margin is preferable for dumping cargo from a tailgate. When opening from the lower margin, a restraint may be employed to limit the amount of opening. When opening from the upper margin, the tailgate typically folds outwardly and extends the surface area of the dump box bed. Regardless of whether it is designed to open at the upper or lower margin, the tailgate typically hinges at that margin to allow the tailgate to pivot about the horizontal of the opposite margin between closed and open positions.
With particular reference to a tailgate configured for opening from the lower margin for dumping material, the gate is designed to open outwardly and to shift bodily upward from the truck body in order to give the greatest possible dumping opening. However, as noted above, it may be desirable to include a restraint to limit the amount of opening according to the cargo being unloaded. Spreader chains are often used for this purpose. By employing spreader chains, the amount of opening of the lower margin of the tailgate can be limited, thereby limiting the rate of discharge of contents from the dump body. Chain holders can be used to set the amount of gate opening upon dumping by selecting the chain links placed in the holder. Typical chain holders comprise an opening in right and left rear corner posts of the dump body, the upper end of the opening being sufficiently large to admit the chain readily, and the lower portion being sufficiently narrow to prevent passage of links of the chain therethrough transverse to the plane of the apertured post face. Various configurations of chain holders, including those projecting from the rear of the dump box, have been developed.
With particular reference to a tailgate configured for opening from the upper margin for unloading cargo, the gate is designed to open outwardly and set on a plane approximately level with the dump box bed. Typically, a latch is provided at each upper corner of the tailgate for retaining the tailgate in its closed position and a flexible element, such as a cable, extends between each upper corner and the upper rear portion of each sidewall of the box for retaining the tailgate in an open position wherein it forms a horizontal extension of the dump box bed.